The rate of mental illness was more than twice as high among those aged 18 to 25 (29.9 percent) than among those aged 50 and older (14.3 percent). Adult women were also more likely than men to have experienced mental illness in the past year (23 percent versus 16.8 percent).

Mental illness among adults aged 18 or older is defined as having had a diagnosable mental, behavioral, or emotional disorder (excluding developmental and substance use disorders) in the past year, based on criteria specified in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association [APA], 1994).

The National Survey on Drug Use and Health also shows that 11.4 million adults (5 percent of the adult population) suffered from serious mental illness in the past year. Serious mental illness is defined as one that resulted in serious functional impairment, which substantially interfered with or limited one or more major life activities.

“Mental illnesses can be managed successfully, and people do recover,” said SAMHSA Administrator Pamela S. Hyde. “Mental illness is not an isolated public health problem. Cardiovascular disease, diabetes, and obesity often co-exist with mental illness and treatment of the mental illness can reduce the effects of these disorders. The Obama Administration is working to promote the use of mental health services through health reform. People, families, and communities will benefit from increased access to mental health services.”

The economic impact of mental illness in the United States is considerable—about $300 billion in 2002. According to the World Health Organization, mental illness accounts for more disability in developed countries than any other group of illnesses, including cancer and heart disease.

In terms of treatment statistics, the report indicates that about 4 in 10 people experiencing any mental illness in the past year (39.2 percent) received mental health services during that period. Among those experiencing serious mental illness, the rate of treatment was notably higher (60.8 percent). The report also noted that an estimated 8.7 million American adults had serious thoughts of suicide in the past year—among them, 2.5 million made suicide plans and 1.1 million attempted suicide.

According to the report, rates for substance dependence were far higher for those who had experienced either any mental illness or serious mental illness than for the adult population which had not experienced mental illness in the past year. Adults experiencing any mental illness in the past year were more than three times as likely to have met the criteria for substance dependence or abuse in that period than those who had not experienced mental illness in the past year (20 percent versus 6.1 percent). Those who had experienced serious mental illness in the past year had even a higher rate of substance dependence or abuse (25.2 percent). “These data underscore the importance of substance abuse treatment as well,” said SAMHSA Administrator Pamela S. Hyde.

“Mental illness is a significant public health problem in itself, but also because it is associated with chronic medical diseases such as cardiovascular disease, diabetes, obesity, and cancer, as well as several risk behaviors including physical inactivity, smoking, excessive drinking, and insufficient sleep,” said Ileana Arias, PhD, principal deputy director of CDC. “Today’s report issued by SAMHSA provides further evidence that we need to continue efforts to monitor levels of mental illness in the United States in order to effectively prevent this important public health problem and its negative impact on total health.”

The report also has important findings regarding mental health issues among those aged 12 to 17. According to the report 1.9 million youth aged 12 to 17 (8 percent of this population) had experienced a major depressive episode in the past year. In addition, the report finds that young people aged 12 to 17 who experienced a major depressive episode in the past year have more than twice the rate of past year illicit drug use (37.2 percent) as their counterparts who had not experienced a major depressive episode during that period (17.8 percent).

The 2010 National Survey on Drug Use and Health is a scientifically conducted annual survey of approximately 67,500 people throughout the country, aged 12 and older.